<template>
    <div class="nav-bar" :class="{'isfixed':isFixed}">
        <div class="container">
            <div class="pro-title">
                {{title}}
            </div>
            <div class="pro-param">
                <a href="javascript:;">概述</a><span> | </span>
                <a href="javascript:;">参数</a><span> | </span>
                <a href="javascript:;">用户评价</a>
                <slot name="buy"></slot>
            </div>
        </div>
    </div>
</template>

<script>
export default {
    name: 'nav-bar',
    props: {
        title: String
    },
    data() {
        return {
            isFixed: false
        }
    },
    mounted() {
        window.addEventListener('scroll', this.initHeight)
    },
    methods: {
        initHeight() {
            const scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
            if (scrollTop > 152) {
                this.isFixed = true
            } else {
                this.isFixed = false
            }
        }
    },
    //  方法抽取出来好进行销毁
    destroyed() {
        //  还有第三个参数，true跟false，决定是用false冒泡还是true捕获
        window.removeEventListener('scroll', this.initHeight, false)
    }
}
</script>

<style lang="scss">
@import './../assets/scss/config.scss';
@import './../assets/scss/mixin.scss';
.nav-bar{
    height: 70px;
    line-height: 70px;
    border-top: 1px solid $colorH;
    z-index: 10;
    &.isfixed{
        position: fixed;
        top: 0;
        width: 100%;
        background-color: $colorG;
        box-shadow: 0 5px 5px $colorE;
    }
    .container{
        @include flex();
        .pro-title{
            font-size: $fontH;
            color: $colorB;
            font-weight: bold;
        }
        .pro-param{
            font-size: $fontJ;
            span{
                margin: 0 10px;
            }
            a{
                color: $colorC;
            }
        }
    }
}
</style>
